Micro-welding using a three-dimensional printer

ABSTRACT

A three-dimensional (3D) printer is configured to introduce a liquid metal onto a first part and a second part while the first part and the second part are in contact with one another. The liquid metal subsequently solidifies to join the first part and the second part together to produce an assembly.

TECHNICAL FIELD

The present teachings relate generally to three-dimensional (3D)printing and, more particularly, to systems and methods formicro-welding two or more parts together using a 3D printer.

BACKGROUND

Gas tungsten arc welding (GTAW), also known as tungsten inert gas (TIG)welding or micro-TIG welding, is an arc welding process that uses anon-consumable tungsten electrode to produce the weld. The weld area andelectrode are protected from oxidation or other atmosphericcontamination by an inert shielding gas (e.g., argon or helium), and afiller metal is normally used.

GTAW is most commonly used to weld thin sections of stainless steel andnon-ferrous metals such as aluminum, magnesium, and copper alloys. Theprocess grants the operator greater control over the weld than competingprocesses such as shielded metal arc welding and gas metal arc welding,allowing for stronger, higher quality welds. However, GTAW iscomparatively more complex and difficult to master, and furthermore, itis slower than most other welding techniques (e.g., less than 2cm/minute).

SUMMARY

The following presents a simplified summary in order to provide a basicunderstanding of some aspects of one or more embodiments of the presentteachings. This summary is not an extensive overview, nor is it intendedto identify key or critical elements of the present teachings, nor todelineate the scope of the disclosure. Rather, its primary purpose ismerely to present one or more concepts in simplified form as a preludeto the detailed description presented later.

A system is disclosed. The system includes a three-dimensional (3D)printer that is configured to introduce a liquid metal onto a first partand a second part while the first part and the second part are incontact with one another. The liquid metal subsequently solidifies tojoin the first part and the second part together to produce an assembly.

In another embodiment, the system includes a gripper configured to gripa first part and a second part in a relative position with respect toone another. The system also includes an arm configured to move thegripper, the first part, and the second part in three dimensions whilethe gripper maintains the first part and the second part in the relativeposition with respect to one another. The system also includes athree-dimensional (3D) printer configured to introduce drops of a liquidmetal onto the first part and the second part simultaneously with thearm moving the gripper, the first part, and the second part. The 3Dprinter is configured to introduce the drops of the liquid metal to forma substantially continuous line of the liquid metal on the first partand the second part at a rate from about 1 cm/second to about 25cm/second, at a frequency from about 300 Hz to about 700 Hz, and with aspacing between drops from about 0.3 mm to about 0.7 mm. The drops ofthe liquid metal have an average cross-sectional length from about 200μm to about 500 μm and an average mass from about 0.10 mg to about 0.30mg. The liquid metal solidifies to join the first part and the secondpart together to produce an assembly.

A method is also disclosed. The method includes holding a first part anda second part in contact with one another. The method also includesmoving the first part and the second part along a movement path whilethe first part and the second part are in contact with one another. Themethod also includes introducing drops of a liquid metal onto the firstpart and the second part using a three-dimensional (3D) printer whilethe first part and the second part are in contact with one another. Theliquid metal solidifies to join the first part and the second parttogether in the position, thereby forming an assembly.

In another embodiment, the method includes holding a first part and asecond part in a relative position with respect to one another. Themethod also includes moving the first part and the second part along amovement path while the first part and the second part are held in therelative position. The method also includes introducing drops of aliquid metal onto the first part, the second part, or both using athree-dimensional (3D) printer while the first part and the second partare held in the relative position.

In another embodiment, the method includes moving a first part along amovement path. The method also includes introducing drops of a liquidmetal onto the first part using a three-dimensional (3D) printer. Thedrops of the liquid metal solidify to form a second part that is joinedto the first part. The method also includes mechanically joining thesecond part to a third part.

In another embodiment, the method includes holding a first part and asecond part in a relative position with respect to one another such thatan end of the first part is adjacent to and faces an end of the secondpart. The method also includes moving the first part and the second partalong a movement path while the first part and the second part are heldin the relative position. The method also includes introducing drops ofa liquid metal onto the first part and the second part using athree-dimensional (3D) printer while the first part and the second partare held in the relative position.

In another embodiment, the method includes holding a first part and asecond part in a relative position with respect to one another such thatan end of the first part is adjacent to and faces an end of the secondpart. The method also includes moving the first part and the second partalong a movement path while the first part and the second part are heldin the relative position. The method also includes depositing first andsecond sets of drops of a liquid metal onto the first part and thesecond part using a three-dimensional (3D) printer while the first partand the second part are held in the relative position. The first andsecond sets of the drops are deposited in a first direction, and thefirst and second sets of the drops are arranged in a second directionthat is different from the first direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the presentteachings and together with the description, serve to explain theprinciples of the disclosure. In the figures:

FIG. 1 depicts a schematic cross-sectional view of system formicro-welding, including a three-dimensional (3D) printer and a moveablearm, according to an embodiment.

FIG. 2 depicts a schematic perspective view of the moveable arm,according to an embodiment.

FIG. 3A depicts a schematic cross-sectional view of a gripper of the armgripping/holding two parts so that the 3D printer can micro-weld the twoparts together to form a tab and slot assembly, according to anembodiment.

FIG. 3B depicts a schematic cross-sectional view of the grippergripping/holding two parts so that the 3D printer can micro-weld the twoparts together to form a butt joint assembly, according to anembodiment.

FIG. 3C depicts a schematic cross-sectional view of the grippergripping/holding two parts so that the 3D printer can micro-weld the twoparts together to form a lap joint assembly, according to an embodiment.

FIG. 3D depicts a schematic cross-sectional view of the grippergripping/holding two parts so that the 3D printer can micro-weld the twoparts together to form a corner joint assembly, according to anembodiment.

FIG. 3E depicts a schematic cross-sectional view of the grippergripping/holding two parts so that the 3D printer can micro-weld the twoparts together to form a tee joint assembly, according to an embodiment.

FIG. 3F depicts a schematic cross-sectional view of the grippergripping/holding two parts so that the 3D printer can micro-weld the twoparts together to form an edge joint assembly, according to anembodiment.

FIG. 3G depicts a schematic cross-sectional view of the grippergripping/holding two parts so that the 3D printer can micro-weld the twoparts together and also deposit additional material onto one or bothparts to form a third part, according to an embodiment.

FIG. 3H depicts a schematic cross-sectional view of the grippergripping/holding the first part so that the 3D printer can print asecond part onto the first part, wherein the second part is configuredto be mechanically joined with a third part, according to an embodiment.

FIGS. 4A-4C depict schematic cross-sectional views of the grippergripping/holding two thick parts so that the 3D printer can micro-weldthe two thick parts together to form a butt joint assembly, according toan embodiment. More particularly, FIG. 4A depicts a first set of dropsof liquid metal deposited on the two parts, FIG. 4B depicts a second setof drops of liquid metal deposited on the two parts, and FIG. 4C depictsa third set of drops of liquid metal deposited on the two parts.

FIGS. 5A-5C depict schematic perspective views of the grippergripping/holding two thin parts so that the 3D printer can micro-weldthe two thin parts together to form a butt joint assembly, according toan embodiment. More particularly, FIGS. 5A and 5B depict multiple setsof drops of liquid metal deposited in a first order, and FIG. 5C depictsmultiple sets of drops of liquid metal deposited in a second, differentorder.

FIG. 6 depicts a flowchart of a method for joining (e.g., micro-welding)together two or more parts, according to an embodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary embodiments of thepresent teachings, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same, similar, or like parts.

FIG. 1 depicts a schematic cross-sectional view of a system 100 forjoining (e.g., micro-welding) two parts together, according to anembodiment. The system 100 may include a 3D printer 105. The 3D printer105 may be or include a magnetohydrodynamic (MHD) printer, which issuitable for jetting liquid metal and its alloys layer upon layer toform a 3D metallic object. As described below, the 3D printer 105 mayalso or instead be configured to jet the liquid metal and its alloys tojoin (e.g., micro-weld) two or more parts together. Thus, the 3Dmetallic object may be or include a weld material that is used to join(e.g., micro-weld) two or more parts together.

The 3D printer 105 may include an enclosure 110. The enclosure 110 mayinclude a lower block 112 and an upper block 114. The lower block 112and/or the upper block 114 may define an inner volume (also referred toas an atmosphere). As described below, a cooling fluid (e.g., water) maycirculate through the inner volume to cool the 3D printer 105 duringprinting operations. The 3D printer 105 may also include a front plate116 that is positioned on an opposite side of the lower block 112 fromthe upper block 114. The front plate 116 may be made of a ceramicmaterial.

The 3D printer 105 may also include an ejector (also referred to as acrucible sleeve) 120. As shown, the ejector 120 may be positioned atleast partially within the inner volume of the enclosure 110. In otherembodiments, the ejector 120 may be positioned outside of the enclosure110. The ejector 120 may be made of boron nitride. The ejector 120 mayalso define an inner volume (also referred to as a cavity). That innervolume of the ejector 120 may have a gas, such as argon or nitrogen,introduced thereto. The ejector 120 may also include a nozzle 122, whichmay extend through the lower block 112, the front plate 116, or both.

The 3D printer 105 may also include a cap 124 positioned at leastpartially within the inner volume of the enclosure 110. For example, thecap 124 may be positioned at least partially between the upper block 114and the ejector 120.

The 3D printer 105 may also include a feedthrough 126 that extendsthrough the upper block 114 and/or the cap 124 into the inner volume ofthe ejector 120. As shown, a printing material 130 may be introducedthrough the feedthrough 126 into the inner volume of the ejector 120.The printing material 130 may be or include a metal, a polymer, or thelike. For example, the printing material 130 may be or include aluminum(e.g., 4008/356, 6061, 7075, etc.), copper, steel, zinc alloys, nickelalloys, or the like. In the example shown in FIG. 1 , the printingmaterial 130 may be or include aluminum (e.g., a spool of aluminumwire).

The 3D printer 105 may also include one or more heating elements 140.The heating elements 140 may be or include graphite coils. As shown, theheating elements 140 may be positioned at least partially within theinner volume of the enclosure 110 and at least partially outside (e.g.,around) the ejector 120. In other embodiments, the heating elements 140may be positioned outside of the enclosure 110. The heating elements 140are configured to melt the printing material 130, thereby converting theprinting material 130 from a solid material to a liquid material (e.g.,liquid aluminum) 132 within the inner volume of the ejector 120.

The 3D printer 105 may also include a melt height sensor 142. The meltheight sensor 142 may be positioned above the upper block 114 and may beconfigured to measure a height and/or volume of the liquid metal 132within the ejector 120 (e.g., using a laser).

The 3D printer 105 may also include one or more metallic coils 150 thatare wrapped at least partially around the ejector 120. A power sourcemay be coupled to the coils 150 and configured to provide an electricalcurrent thereto. In one embodiment, the power source may be configuredto provide a step function direct current (DC) voltage profile (e.g.,voltage pulses) to the coils 150, which may create an increasingmagnetic field. The increasing magnetic field may cause an electromotiveforce within the ejector 120, that in turn causes an induced electricalcurrent in the liquid metal 132. The magnetic field and the inducedelectrical current in the liquid metal 132 may create a radially inwardforce on the liquid metal 132, known as a Lorenz force. The Lorenz forcecreates a pressure at an inlet of the nozzle 122. The pressure causesthe liquid metal 132 to be jetted through the nozzle 122 in the form ofone or more drops 134.

The 3D printer 105 may also include a sleeve 160 that is positioned atleast partially within the inner volume of the enclosure 110. The sleeve160 may be or include a gold-plated quartz sleeve that is positioned atleast partially (e.g., radially) between the ejector 120 and the coils150. In at least one embodiment, a shield gas, such as argon ornitrogen, may be positioned between the ejector 120 and the sleeve 160.

The system 100 may also include a moveable arm 200. The arm 200 may bepositioned at least partially above or below the 3D printer 105. Forexample, the arm 200 may be positioned at least partially above or belowthe nozzle 122. The arm 200 may include a gripper (also referred to as afixture) 250 that is configured to hold two or more parts while the 3Dprinter 105 joins (e.g., micro-welds) them together, as discussed below.The arm 200 may position the gripper relative to the nozzle 122 (e.g.,above or below the nozzle 122). The arm 200 may be configured to movethe gripper 250 and the two or more parts therein in one, two, or threedimensions. The arm 200 may also or instead be configured to pivot orrotate the gripper 250 and the two or more parts therein in one, two, orthree dimensions. In one embodiment, the arm 200 and/or the gripper 250may have a heater 252 coupled thereto and/or positioned therein.

The system 100 may also include a computing system 170 that may beconfigured to control the 3D printer 105, the arm 200, or both. Forexample, the computing system may be configured to control the ejectionof the drops 134 from the nozzle 122 and control the movement of the arm200. Thus, as discussed in greater detail below, the computing system170 may be configured to cause the arm 200 to move the gripper 250 andthe parts therein through a predetermined movement path under the nozzle122 while simultaneously causing the 3D printer 105 to jet/deposit thedrops 134 onto the parts to join (e.g., micro-weld) the parts together.

FIG. 2 depicts a schematic perspective view of the arm 200, according toan embodiment. The arm 200 may include a base 210, one or more segments(two are shown: 220, 230), one or more joints (five are shown: 241-245),the gripper 250, or a combination thereof. In the embodiment shown, thebase 210 may be coupled to a first end 222 of the first arm 220 via oneor more of the joints (e.g., joints 241, 242), a second end 224 of thefirst arm 220 may be coupled to a first end 232 of the second arm 230via one or more of the joints (e.g., joint 243), and a second end 234 ofthe second arm 230 may be coupled to the gripper 250 via one or more ofthe joints (e.g., joints 244, 245).

The first joint 241 may allow the base 210 and/or the first segment 220to pivot or rotate around a central longitudinal axis 261 through thebase 210, as shown by the arrow 271. The second joint 242 may allow thefirst segment 220 to pivot or rotate around an axis 262 through thefirst end 222 of the first segment 220, as shown by the arrow 272. Theaxes 261, 262 may be substantially perpendicular to one another. Thethird joint 243 may allow the second segment 230 to pivot or rotatearound an axis 263 through the second end 224 of the first segment 220and/or the first end 232 of the second segment 230, as shown by thearrow 273. The axes 262, 263 may be substantially parallel to oneanother. The fourth joint 244 may allow the gripper 250 to pivot orrotate around an axis 264 through the second end 234 of the secondsegment 230, as shown by the arrow 274. The axes 263, 264 may besubstantially parallel to one another. The fifth joint 245 may allow thegripper 250 to pivot or rotate around an axis 265 through the second end234 of the second segment 230, as shown by the arrow 275. The axes 264,265 may be substantially perpendicular to one another.

Thus, as mentioned above, the segments 220, 230 and joints 241-245 mayallow the gripper 250 to move, pivot, and/or rotate in one, two, orthree dimensions with respect to the 3D printer 105 (e.g., with respectto the nozzle 122). In another embodiment, the nozzle 122 may also orinstead be configured to move, pivot, or rotate in one, two, or threedimensions with respect to the arm 200 (e.g., with respect to thegripper 250).

FIGS. 3A-3F depict schematic views of the gripper 250 gripping/holdingtwo or more parts so that the parts may be joined (e.g., micro-welded)together by a weld material 340 that is deposited by the 3D printer 105,according to an embodiment. The parts and/or the weld material 340 maybe made from metal, polymer, ceramic, or a combination thereof. In oneembodiment, the parts and/or the weld material 340 may be made frommaterials that are weld compatible to/with each other. For example, theparts and/or the weld material 340 may be made from the same material.The material for the parts and/or the weld material 340 may be orinclude aluminum (e.g., 4008/356, 6061, 7075, etc.), copper, steel, zincalloys, nickel alloys, or the like. In an example, the parts may be orinclude pre-cut sheet stock, castings, bar or plate stock, tubularstock, pre-machined or otherwise formed components, etc.

More particularly, FIG. 3A depicts a schematic cross-sectional view oftwo parts 310A, 320A positioned at least partially within (e.g., beinggripped/held by) the gripper 250. As shown, the first part 310A mayinclude a slot 312A, and the second part 320A may include a tab 322Athat is configured to be positioned at least partially within the slot312A. For example, the tab 322A may be inserted into the slot 312A, andthe gripper 250 may hold the parts 310A, 320A in this position relativeto one another. The 3D printer 105 may then deposit the drops 134 ontothe parts 310A, 320A. More particularly, the 3D printer 105 may depositthe drops 134 onto an intersection between the parts 310A, 320A. Thedrops 134 may solidify to form a weld material 340 that joins (e.g.,micro-welds) the parts 310A, 320A together as a tab and slot assembly330A.

FIG. 3B depicts another schematic cross-sectional view of two parts310B, 320B positioned at least partially within (e.g., beinggripped/held by) the gripper 250. As shown, an end 312B of the firstpart 310 may be positioned adjacent to an end 322B of the second part320B. The ends 312B, 322B may be spaced apart by a predetermineddistance (e.g., from about 0.1 mm to about 5 mm or about 0.5 mm to about2 mm) such that a gap is present between the ends 312B, 322B, and thegripper 250 may hold the parts 310B, 320B in this position relative toone another. The 3D printer 105 may then deposit the drops 134 into thegap between the parts 310B, 320B such that the drops 134 contact bothends 312B, 322B. The drops 134 may solidify to form the weld material340 that joins (e.g., micro-welds) the parts 310B, 320B together as abutt joint assembly 330B.

FIG. 3C depicts another schematic cross-sectional view of two parts310C, 320C positioned at least partially within (e.g., beinggripped/held by) the gripper 250. The parts 310C, 320C may be at leastpartially overlapping one another. For example, a side 312C of the firstpart 310C may be in contact with a side 322C of the second part 320C.The gripper 250 may hold the parts 310C, 320C in this position relativeto one another. The 3D printer 105 may then deposit a first set of drops134 into contact with the side 312C of the first part 310C and an end324C of the second part 320C, and a second set of drops 134 into contactwith the side 322C of the second part 320C and an end 314C of the firstpart 310C. The drops 134 may solidify to form the weld material 340 thatjoins (e.g., micro-welds) the parts 310C, 320C together as a lap jointassembly 330C.

FIG. 3D depicts another schematic cross-sectional view of two parts310D, 320D positioned at least partially within (e.g., beinggripped/held by) the gripper 250. As shown, an end 312D of the firstpart 310D may be in contact with a side 324D of the second part 320D. Inthis particular embodiment, the end 312D may be located closer to an end322D of the second part 320D than a middle 326D of the second part 320D.The gripper 250 may hold the parts 310D, 320D in this position relativeto one another. The 3D printer 105 may then deposit the drops 134 intocontact with sides 314D, 315D of the first part 310D and the side 324Dof the second part 320D. The drops 134 may solidify to form the weldmaterial 340 that joins (e.g., micro-welds) the parts 310D, 320Dtogether as a corner joint assembly 330D.

FIG. 3E depicts another schematic cross-sectional view of two parts310E, 320E positioned at least partially within (e.g., beinggripped/held by) the gripper 250. As shown, an end 312E of the firstpart 310E may be in contact with a side 324E of the second part 320E. Inthis particular embodiment, the end 312E may be located at or proximateto a middle 326E of the second part 320E. The gripper 250 may hold theparts 310E, 320E in this position relative to one another. The 3Dprinter 105 may then deposit the drops 134 into contact with sides 314E,315E of the first part 310E and the side 324E of the second part 320E.The drops 134 may solidify to form the weld material 340 that joins(e.g., micro-welds) the parts 310E, 320E together as a tee jointassembly 330E.

FIG. 3F depicts another schematic cross-sectional view of two parts310F, 320F positioned at least partially within (e.g., beinggripped/held by) the gripper 250. As shown, a side 314F of the firstpart 310F may be in contact with a side 324F of the second part 320F. Inthis embodiment, the second part 320F is substantially curved and/orL-shaped; however, in other embodiments, the second part 320F may besubstantially straight. The 3D printer 105 may then deposit the drops134 into contact with ends 312F, 322F of the parts 310F, 320F. The drops134 may solidify to form the weld material 340 that joins (e.g.,micro-welds) the parts 310F, 320F together as an edge joint assembly330F. In at least one embodiment, neither the drops 134 nor the weldmaterial 340 may contact the sides 314F, 315F, 324F, 325F of the parts310F, 320F.

FIG. 3G depicts another schematic cross-sectional view of two parts310G, 320G positioned at least partially within (e.g., beinggripped/held by) the gripper 250. The first and second parts 310G, 320Gmay be or include sheet stock. The first part 310G may be in contactwith the second part 320G. The 3D printer 105 may deposit a first set ofdrops 134 onto the parts 310G, 320G proximate to where the parts 310G,320G contact one another. The first set of drops 134 may solidify toform the weld material 340 that joins (e.g., micro-welds) the parts310G, 320G together to form an assembly.

In addition, before or after the parts 310G, 320G are joined together,the printer 105 may also deposit a second set of drops 134 onto thefirst part 310G, the second part 320G, or both. In the example shown,the second set of drops 134 may be deposited on the first part 310G butnot the second part 320G. In another example, the second set of drops134 may be deposited on the second part 320G but not the first part320G. In yet another example, the second set of drops 134 may contactboth parts 310G, 320G. The second set of drops 134 may cool and solidifyto form a third part 350G. In the example shown, the third part 350G isjoined with the first part 310G but not the second part 320G. In thisparticular example, neither the second set of drops 134 nor the thirdpart 350G may be used to join the parts 310G, 320G together. In otherwords, the third part 350G may serve a different function than joiningthe parts 310G, 320G together.

FIG. 3H depicts another schematic cross-sectional view of a first part310H positioned at least partially within (e.g., being gripped/held by)the gripper 250. In one or more of the examples above, the parts310A-310G, 320A-320G and/or the weld material 340 are made frommaterial(s) that is/are weld compatible with one another. For example,the parts the parts 310A-310G, 320A-320G and/or the weld material 340may be made from the same material.

However, in the example in FIG. 3H, one of the parts 320H is made from amaterial that is not weld compatible (or is less weld compatible) withthe other part 310H and/or the weld material 340. For example, thesecond part 320H may be made from a different material than the firstpart 310H and/or the weld material 340. In other words, the weldmaterial 340 may not bond to the second part 320H as well as it bonds tothe first part 310H. As a result, the parts 310H, 320H may not be joined(e.g., micro-welded) together in the same manner as described abovebecause the weld material 340 may not form a sufficient bond to/with thesecond part 320H.

The first part 310H and/or the weld material 340 may be made fromaluminum (e.g., 4008/356, 6061, 7075, etc.), copper, steel, zinc alloys,nickel alloys, or the like. The second part 320H may be made from amaterial that can be in contact with the high heat (e.g., 500° C.+)generated by the MHD process without deformation or degradation. Forexample, the second part 320H may be made from titanium, tungsten,stainless steel, brass, bronze, silicon carbide, ceramic, glass, naturalstone, cement, silicone, etc.

The second part 320H may be positioned outside of the gripper 250 (asshown), or the second part 320H may be positioned at least partiallywithin the gripper 250 (not shown). The weld material 340 may bedeposited onto the first part 310H, and the weld material 340 may cooland solidify to form a third part 350H that is joined (e.g.,micro-welded) to the first part 310H. The third part 350H may be shapedand sized to mechanically join/lock with the second part 320H (e.g., viaa dovetail joint, pin style joint, tapered mortise and tendon, taperedtongue and groove, etc.) Thus, the third part 350H may be used tomechanically join/lock the first and second parts 310H, 320H together toform the assembly. In one example, the second and third parts 320H, 350Hmay be mechanically joined/locked together using the 3D printer 105, thearm 200, the gripper 250, or a combination thereof. In another example,the second and third parts 320H, 350H may be mechanically joined/lockedtogether manually after one or both is/are removed from the gripper 250.In another embodiment, the joint may also or instead be held togetherwith a fastener (e.g., a screw, a rivet, a pin, etc.), and the 3Dprinter 105 may deposit the weld material 340 to build the fastener intothe joint.

FIGS. 4A-4C illustrate schematic cross-sectional views of two thickparts 410, 420 being joined (e.g., micro-welded) together to form a buttjoint assembly. The parts 410, 420 may be or include plates. The parts410, 420 may have a thickness 454 from about 1 mm to about 50 mm orabout 3 mm to about 50 mm. Ends 412, 422 of the parts 410, 420 may bechamfered. Thus, an upper surface 414 of the end 412 may be oriented atan angle 450 with respect to an upper surface 424 of the end 422. Theangle 450 may be from about 10° to about 150°, about 30° to about 120°,or about 50° to about 90°. Similarly, a lower surface 416 of the end 412may be oriented at an angle 452 with respect to a lower surface 426 ofthe end 422. The angle 452 may be from about 10° to about 150°, about30° to about 120°, or about 50° to about 90°.

In one embodiment, the ends 412, 422 may be in contact with one another.As shown, in another embodiment, the ends 412, 422 may be adjacent toone another (e.g., facing one another); however, a gap may exist betweenthe ends 412, 422. The gap may be from about 0.1 mm to about 5 mm, orabout 0.5 mm to about 3 mm. As shown in FIG. 4A, a first set of thedrops 134A may be deposited at least partially between the ends 412,422. The first set of drops may contact both ends 412, 422. The firstset of drops 134A may be positioned proximate to an inner (e.g., middleportion) of the ends 412, 422 (e.g., proximate to the chamfered pointsof the ends 412, 422).

As shown in FIG. 4B, a second set of drops 134B may be deposited afterthe first set of drops 134A is deposited. The second set of drops 134Bmay be positioned at least partially between the ends 412, 422. Thesecond set of drops 134B may contact both ends 412, 422. The second setof drops 134B may be positioned at least partially around the first setof drops 134A. For example, as shown in FIG. 4B, the second set of drops134B may be positioned above and/or below the first set of drops 134A.Due to the angles 450, 452 at which the ends 412, 422 are oriented, thesecond set of drops 134B may have a greater width than the first set ofdrops 134A.

As shown in FIG. 4C, a third set of drops 134C may be deposited afterthe second set of drops 134B is deposited. The third set of drops 134Cmay be positioned at least partially between the ends 412, 422. Thethird set of drops 134C may contact both ends 412, 422. The third set ofdrops 134C may be positioned at least partially around the first set ofdrops 134A and/or the second set of drops 134B. For example, as shown inFIG. 4C, the third set of drops 134C may be positioned above and/orbelow the second set of drops 134B. The third set of drops 134C may bepositioned proximate to outer portions of the ends 412, 422 and distalto the middle portion of the ends 412, 422. In other words, the thirdset of drops 134C may be positioned proximate to upper and/or lowersurfaces of the parts 410, 420. Due to the angles 450, 452 at which theends 412, 422 are oriented, the third set of drops 134C may have agreater width than the second set of drops 134B.

The drops 134A-134C may cool and solidify to form the weld material 340that joins (e.g., micro-welds) the parts 410, 420 together as the buttjoint assembly. In one embodiment, the first set of drops 134A may atleast partially cool and/or solidify prior to the second set of drops134B being deposited, and the second set of drops 134B may at leastpartially cool and/or solidify prior to the third set of drops 134Cbeing deposited. In another embodiment, the second set of drops 134B maybe deposited onto the first set of drops 134A while the first set ofdrops 134A is still in a substantially liquid state, and the third setof drops 134C may be deposited onto the second set of drops 134B whilethe second set of drops 134A is still in a substantially liquid state.In this embodiment, the drops 134A-134C may cool and solidify together.

FIGS. 5A-5C illustrate schematic perspective views of two thin parts510, 520 being joined (e.g., micro-welded) together to form a butt jointassembly 530. The parts 510, 520 may be or include plates. The parts510, 520 may have a thickness 554 from about 0.2 mm to about 2 mm. Ends512, 522 of the parts 510, 520 may be chamfered. For example, the endsmay be oriented at an angle with respect one another such that adistance between the ends increases proceeding in a vertical direction(e.g., upward). The angle may be from about 10° to about 150°, about 30°to about 120°, or about 50° to about 90°.

As shown in FIGS. 5A and 5B, the drops may be deposited in a pluralityof sets (four are shown: 134A-134D). Each set of drops 134A-134D may bedeposited in a first direction 560; however, the sets of drops 134A-134Dmay be ordered/arranged in a second direction 562 that is different than(e.g., opposite to) the first direction 560. In other words, thedifferent sets of drops 134A-134D are not printed directly adjacent toeach other, for the reasons described below.

In the example shown, the arm 200 may move the gripper 250 and the parts510, 520 in the second direction 562 with respect to the nozzle 122 toallow the first set of drops 134A to be deposited in the first direction560, as shown by arrow 571. After the first set of drops 134A has beendeposited, the arm 200 may move the gripper 250 and the parts 510, 520in the first direction 560 with respect to the nozzle 122, as shown bythe arrow 581 in FIG. 5B. Then, the arm 200 may move the gripper 250 andthe parts 510, 520 in the second direction 562 with respect to thenozzle 122 to allow the second set of drops 134B to be deposited in thefirst direction 560, as shown by arrow 572, such that the second set ofdrops 134B proceeds toward the first set of drops 134A. After the secondset of drops 134B has been deposited, the arm 200 may move the gripper250 and the parts 510, 520 in the first direction 560 with respect tothe nozzle 122, as shown by the arrow 582 in FIG. 5B. Then, the arm 200may move the gripper 250 and the parts 510, 520 in the second direction562 with respect to the nozzle 122 to allow the third set of drops 134Cto be deposited in the first direction 560, as shown by arrow 573, suchthat the third set of drops 134C proceeds toward the second set of drops134B. After the third set of drops 134C has been deposited, the arm 200may move the gripper 250 and the parts 510, 520 in the first direction560 with respect to the nozzle 122. Then, the arm 200 may move thegripper 250 and the parts 510, 520 in the second direction 562 withrespect to the nozzle 122 to allow the fourth set of drops 134D to bedeposited in the first direction 560, as shown by arrow 574, such thatthe fourth set of drops 134D proceeds toward the third set of drops134C.

The sets of drops 134A-134D may thus be arranged in the following orderin the second direction 562: first set of drops 134A, second set ofdrops 134B, third set of drops 134C, fourth set of drops 134D. The setsof drops 134A-134D may cool and solidify to form the weld material 340that joins (e.g., micro-welds) the parts 510, 520 together to form thebutt joint assembly 530.

In FIG. 5C, the sets of drops 134A-134D may be deposited in the firstdirection 560, similar to FIGS. 5A and 5B; however, the sets of drops134A-134D may be arranged in a different order. More particularly, thesets of drops 134A-134D may be arranged in the following order in thesecond direction 562: first set of drops 134A, third set of drops 134C,second set of drops 134B, fourth set of drops 134D. The benefit ofperforming this type of operation is to more evenly distribute thethermal input to the parts 510, 520 that are being joined. This is doneby leaving a space between the most recently joined section and the nextsection to be joined, and then later going back to complete the areathat was bypassed initially. This is advantageous in micro-welding thinmetals because the risk for part deformation due to thermal stress isreduced. The sets of drops 134A-134D may cool and solidify to form theweld material 340 that joins (e.g., micro-welds) the parts 510, 520together to form the butt joint assembly 530.

In the example shown, the arm 200 may move the gripper 250 and the parts510, 520 in the second direction 562 with respect to the nozzle 122 toallow the first set of drops 134A to be deposited in the first direction560, as shown by arrow 571. After the first set of drops 134A has beendeposited, the arm 200 may move the gripper 250 and the parts 510, 520in the first direction 560 with respect to the nozzle 122. Then, the arm200 may move the gripper 250 and the parts 510, 520 in the seconddirection 562 with respect to the nozzle 122 to allow the second set ofdrops 134B to be deposited in the first direction 560, as shown by arrow572, such that the second set of drops 134B proceeds toward the firstset of drops 134A. However, a gap may be present between the first andsecond sets of drops 134A, 134B. After the second set of drops 134B hasbeen deposited, the arm 200 may move the gripper 250 and the parts 510,520 in the first direction 560 with respect to the nozzle 122. Then, thearm 200 may move the gripper 250 and the parts 510, 520 in the seconddirection 562 with respect to the nozzle 122 to allow the third set ofdrops 134C to be deposited in the gap between the first and second setsof drops 134A, 134B. The third set of drops 134C may be deposited in thefirst direction 560, as shown by arrow 573, such that the third set ofdrops 134C proceeds toward the first set of drops 134A and away from thesecond set of drops 134B. After the third set of drops 134C has beendeposited, the arm 200 may move the gripper 250 and the parts 510, 520in the first direction 560 with respect to the nozzle 122. Then, the arm200 may move the gripper 250 and the parts 510, 520 in the seconddirection 562 with respect to the nozzle 122 to allow the fourth set ofdrops 134D to be deposited in the first direction 560, as shown by arrow574, such that the fourth set of drops 134D proceeds toward the secondset of drops 134B.

FIG. 6 depicts a flowchart of a method 600 for joining (e.g.,micro-welding) two or more parts together, according to an embodiment.An illustrative order of the method 600 is provided below; however, oneor more steps may be performed in a different order, performedsimultaneously, repeated, or omitted. The method 600 may be performed bythe system 100.

The method 600 may include holding two or more parts in a relativeposition with respect to one another using the gripper 250, as at 602.One or both parts may be held/gripped by the gripper 250. Illustrativepositions are shown in FIGS. 3A-3H. The parts may be held in contactwith one another, or the parts may be held with a small gap therebetweenfrom about 0.1 mm to about 5 mm.

The method 600 may also include determining a movement path of the arm200 and/or the gripper 250, as at 604. For example, the computing system170 may determine a computer numerically controlled (CNC) movement pathfor the arm 200 and/or the gripper 250 with respect to the nozzle 122.The movement path may be based at least partially upon the relativeposition of the parts with respect to one another (e.g., in the gripper250), the orientation of the parts with respect to one another, theposition of the parts with respect to the nozzle 122, the orientation ofthe parts with respect to the nozzle 122, the size of the parts, theshape of the parts, the material of the parts, or a combination thereof.

The method 600 may also include moving the gripper 250 along themovement path using the arm 200, as at 606. The movement path maydetermine how the arm 200 moves the location of the gripper 250 (and theparts) in one, two, or three dimensions with respect to the 3D printer105 (e.g., with respect to the nozzle 122). The movement path may alsoor instead determine how the arm 200 rotates or pivots the gripper 250(and the parts) in one, two, or three dimensions with respect to the 3Dprinter 105 (e.g., with respect to the nozzle 122).

This step may cause relative movement between the nozzle 122 and theparts. In the embodiment shown, the part(s) may be gripped by thegripper 250, and the parts and the gripper 250 may move through themovement path while the nozzle 122 remains substantially stationary. Inanother embodiment, the 3D printer 105 and/or the nozzle 122 may becoupled to the arm 200 and moved through the movement path using the arm200 while the part(s) remain substantially stationary.

As the arm 200 moves the gripper 250 through the movement path, alocation on the parts (e.g., an intersection between the parts) that isto receive the drops 134/weld material 340 passes in front of (e.g.,below) the nozzle 122. While moving through the movement path, adistance between the nozzle 122 and the location on the parts (e.g., anintersection between the parts) that is to receive the drops 134/weldmaterial 340 may be maintained from about 0.5 mm and about 10 mm, orfrom about 1 mm to about 5 mm. For example, the distance may remainsubstantially constant.

The method 600 may also include heating one or both parts, as at 608. Inone embodiment, the part(s) may be heated prior to being gripped by thegripper 250. In another embodiment, the part(s) may be heated whilebeing gripped by the gripper 250 by the heater 252 that is coupled toand/or positioned within the gripper 250. The part(s) may be heated to atemperature from about 100° C. to about 600° C., about 300° C. to about550° C., or about 400° C. to about 500° C. prior to the drops 134 of theliquid metal being jetted/deposited onto the part(s).

The method 600 may also include jetting/depositing the drops of liquidmetal 134 onto the parts (e.g., including the intersection between theparts) using the 3D printer 105, as at 610. The drops 134 may have anaverage cross-sectional length (e.g., diameter) from about 100 μm toabout 800 μm or about 200 μm to about 500 μm. The drops 134 may have amass from about 0.05 mg to about 0.50 mg, about 0.10 mg to about 0.30mg, or about 0.15 mg to about 0.20 mg. The drops 134 may bejetted/deposited at a rate from about 50 Hz to about 1000 Hz or about100 Hz to about 500 Hz. The spacing between drops 134 may be from about0.1 mm to about 2 mm, about 0.1 mm to about 0.5 mm, about 0.5 mm toabout 1 mm, or about 1 mm to about 2 mm.

In at least one embodiment, steps 606, 608, and/or 610 may be performedsimultaneously. As a result, the drops 134 may be deposited to form aline of the liquid metal on the parts, including the intersectionbetween the parts. The line may be continuous, or in discrete intervalswith gaps therebetween (i.e., spaced-apart drops 134). The line may bestraight or curved. The line may be formed at a rate from about 0.1cm/second to about 25 cm/second, about 0.5 cm/second to about 1cm/second, about 1 cm/second to about 3 cm/second, about 3 cm/second toabout 5 cm/second, about 5 cm/second to about 10 cm/second, or about 10cm/second to about 25 cm/second. This is faster than conventional TIGmicro-welding techniques. For example, the drops 134 may bejetted/deposited at a rate of about 500 Hz with a spacing between dropsof about 0.5 mm, resulting in the line being formed at a rate from about10 cm/second to about 25 cm/second. The line may have a length fromabout 1 mm to about 100 cm, about 1 mm to about 1 cm, about 1 cm toabout 10 cm, or about 10 cm to about 100 cm. The line may have a widthfrom about 0.4 mm to about 2 mm or about 0.55 mm to about 1.5 mm. Forexample, the nominal or average width may be about 0.7 mm. The line mayhave a height from about 0.01 mm to about 0.4 mm or about 0.03 mm toabout 0.24 mm. For example, the nominal or average height may be about0.15 mm.

The line of liquid metal formed by the drops 134 may solidify to form aline of the weld material 340, which may join (e.g., micro-weld) thepart together to form the assembly. This may be referred to asmicro-structure welding. The method 600 may also include removing theassembly from the gripper 250, as at 612. The method 600 may then loopback to 602 and repeat with new/different parts.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the present teachings are approximations, thenumerical values set forth in the specific examples are reported asprecisely as possible. Any numerical value, however, inherently containscertain errors necessarily resulting from the standard deviation foundin their respective testing measurements. Moreover, all ranges disclosedherein are to be understood to encompass any and all sub-ranges subsumedtherein. For example, a range of “less than 10” may include any and allsub-ranges between (and including) the minimum value of zero and themaximum value of 10, that is, any and all sub-ranges having a minimumvalue of equal to or greater than zero and a maximum value of equal toor less than 10, e.g., 1 to 5.

While the present teachings have been illustrated with respect to one ormore implementations, alterations and/or modifications may be made tothe illustrated examples without departing from the spirit and scope ofthe appended claims. For example, it may be appreciated that while theprocess is described as a series of acts or events, the presentteachings are not limited by the ordering of such acts or events. Someacts may occur in different orders and/or concurrently with other actsor events apart from those described herein. Also, not all processstages may be required to implement a methodology in accordance with oneor more aspects or embodiments of the present teachings. It may beappreciated that structural objects and/or processing stages may beadded, or existing structural objects and/or processing stages may beremoved or modified. Further, one or more of the acts depicted hereinmay be carried out in one or more separate acts and/or phases.Furthermore, to the extent that the terms “including,” “includes,”“having,” “has,” “with,” or variants thereof are used in either thedetailed description and the claims, such terms are intended to beinclusive in a manner similar to the term “comprising.” The term “atleast one of” is used to mean one or more of the listed items may beselected. Further, in the discussion and claims herein, the term “on”used with respect to two materials, one “on” the other, means at leastsome contact between the materials, while “over” means the materials arein proximity, but possibly with one or more additional interveningmaterials such that contact is possible but not required. Neither “on”nor “over” implies any directionality as used herein. The term“conformal” describes a coating material in which angles of theunderlying material are preserved by the conformal material. The term“about” indicates that the value listed may be somewhat altered, as longas the alteration does not result in nonconformance of the process orstructure to the illustrated embodiment. The terms “couple,” “coupled,”“connect,” “connection,” “connected,” “in connection with,” and“connecting” refer to “in direct connection with” or “in connection withvia one or more intermediate elements or members.” Finally, the terms“exemplary” or “illustrative” indicate the description is used as anexample, rather than implying that it is an ideal. Other embodiments ofthe present teachings may be apparent to those skilled in the art fromconsideration of the specification and practice of the disclosureherein. It is intended that the specification and examples be consideredas exemplary only, with a true scope and spirit of the present teachingsbeing indicated by the following claims.

What is claimed is:
 1. A system, comprising: a three-dimensional (3D)printer configured to deposit drops of a liquid metal onto a first partand a second part, wherein a first set of the drops and a second set ofthe drops are aligned, wherein the second set of the drops is positionedcloser to a beginning of the depositing of the first set of the dropsthan to an end of the depositing of the first set of the drops, andwherein the liquid metal subsequently solidifies to join the first partand the second part together to produce an assembly.
 2. The system ofclaim 1, further comprising: a gripper configured to hold the first partand the second part in contact with one another; and an arm configuredto move the gripper, the first part, and the second part simultaneouslywith the 3D printer introducing the liquid metal onto the first part andthe second part.
 3. The system of claim 2, wherein the arm comprises twoor more segments and two or more joints, which allow the arm to: movethe gripper, the first part, and the second part in three dimensionssimultaneously with the 3D printer introducing the liquid metal onto thefirst part and the second part; and rotate the gripper, the first part,and the second part in three dimensions simultaneously with the 3Dprinter introducing the liquid metal onto the first part and the secondpart.
 4. The system of claim 2, wherein the gripper is configured togrip the first part and the second part while a tab of the first part ispositioned at least partially within a slot of the second part, andwherein the 3D printer is configured to introduce the liquid metal ontothe first part and the second part proximate to an intersection of thetab and the slot.
 5. The system of claim 2, wherein the gripper isconfigured to grip the first part and the second part such that a gap isdefined therebetween, wherein the 3D printer is configured to introducethe liquid metal into the gap such that the liquid metal contacts an endof the first part and an end of the second part, and wherein theassembly comprises a butt joint assembly.
 6. The system of claim 2,wherein the gripper is configured to grip the first part and the secondpart such that a side of the first part is in contact with a side of thesecond part, wherein the 3D printer is configured to introduce theliquid metal onto the side of the first part and onto an end of thesecond part, and wherein the assembly comprises a lap joint assembly. 7.The system of claim 2, wherein the gripper is configured to grip thefirst part and the second part such that an end of the first part is incontact with a side of the second part, wherein the 3D printer isconfigured to introduce the liquid metal onto a side of the first partand onto the side of the second part, and wherein the assembly comprisesa corner joint assembly or a tee joint assembly.
 8. The system of claim2, wherein the gripper is configured to grip the first part and thesecond part such that a side of the first part is in contact with a sideof the second part, wherein the 3D printer is configured to introducethe liquid metal onto an end of the first part and onto an end of thesecond part, and wherein the assembly comprises an edge joint assembly.9. The system of claim 1, wherein the 3D printer is configured todeposit the liquid metal along an intersection of the first part and thesecond part at a rate from about 0.1 cm/second to about 25 cm/second, ata frequency from about 200 Hz to about 800 Hz, and with a spacingbetween the drops from about 0.2 mm to about 0.8 mm.
 10. The system ofclaim 1, wherein the 3D printer is configured to introduce the dropsonto the first part and the second part, wherein the drops have anaverage cross-sectional length from about 100 μm to about 800 μm and anaverage mass from about 0.05 mg to about 0.50 mg.
 11. A system,comprising: a gripper configured to hold a first part and a second partin a relative position with respect to one another; an arm configured tomove the gripper, the first part, and the second part in threedimensions while the gripper holds the first part and the second part inthe relative position with respect to one another; and athree-dimensional (3D) printer configured to deposit drops of a liquidmetal onto the first part, the second part, or both while the gripperholds the first part and the second part in the relative position withrespect to one another, wherein the 3D printer is configured tointroduce the drops of the liquid metal at a rate from about 1 cm/secondto about 25 cm/second onto the first part, the second part, or both,wherein the 3D printer is configured to introduce the drops of theliquid metal at a frequency from about 50 Hz to about 1000 Hz onto thefirst part, the second part, or both, wherein a first set of the dropsand a second set of the drops are aligned, wherein the second set of thedrops is positioned closer to a beginning of the depositing of the firstset of the drops than to an end of the depositing of the first set ofthe drops, and wherein the liquid metal solidifies to join the firstpart and the second part together to produce an assembly.
 12. The systemof claim 11, wherein the 3D printer is configured to introduce the dropsof the liquid metal onto the first part and the second part while thearm moves the gripper, the first part, and the second part.
 13. Thesystem of claim 11, wherein the 3D printer is configured to introducethe drops of the liquid metal onto the first part and the second partduring pauses between when the arm moves the gripper, the first part,and the second part.
 14. The system of claim 11, wherein a spacingbetween the drops of the liquid metal on the first part, the secondpart, or both is from about 0.1 mm to about 1 mm.
 15. The system ofclaim 11, wherein the drops of the liquid metal have an averagecross-sectional length from about 100 μm to about 1000 μm and an averagemass from about 0.05 mg to about 0.50 mg.
 16. A system, comprising: agripper configured to hold a first part and a second part in a relativeposition with respect to one another; an arm configured to move thegripper, the first part, and the second part in three dimensions whilethe gripper holds the first part and the second part in the relativeposition with respect to one another; and a three-dimensional (3D)printer configured to deposit drops of a liquid aluminum onto the firstpart and the second part simultaneously with the arm moving the gripper,the first part, and the second part, wherein the 3D printer isconfigured to introduce the drops at a rate from about 1 cm/second toabout 25 cm/second and at a frequency from about 300 Hz to about 700 Hz,wherein a spacing between the drops on the first part and the secondpart is from about 0.3 mm to about 0.7 mm, wherein the drops have anaverage cross-sectional length from about 200 μm to about 500 μm and anaverage mass from about 0.10 mg to about 0.30 mg, wherein a first set ofthe drops and a second set of the drops are aligned, wherein the secondset of the drops is positioned closer to a beginning of the depositingof the first set of the drops than to an end of the depositing of thefirst set of the drops, and wherein the drops solidify to join the firstpart and the second part together to produce an assembly.
 17. The systemof claim 16, wherein the arm is also configured to rotate the gripper,the first part, and the second part in three dimensions while thegripper holds the first part and the second part in the relativeposition with respect to one another.
 18. The system of claim 17,wherein the 3D printer is also configured to introduce the drops of theliquid aluminum onto the first part and the second part simultaneouslywith the arm rotating the gripper, the first part, and the second part.19. The system of claim 16, wherein the 3D printer is configured tointroduce the drops of the liquid aluminum to form a line of the liquidaluminum on the first part and the second part, and wherein the line hasa length from about 1 mm to about 100 cm, a width from about 0.4 mm toabout 2 mm, and a height from about 0.01 mm to about 0.4 mm.
 20. Thesystem of claim 16, wherein the arm is configured to maintain a distancebetween a nozzle of the 3D printer and locations on the first part andthe second part onto which the drops of the liquid aluminum aredeposited while the arm moves the gripper, the first part, and thesecond part, and wherein the distance is from about 1 mm to about 5 mm.